John T. Patton is a non-tenured Assistant Professor in the Department of Microbiology and Immunology and the University of Miami School of Medicine. Dr. Patton initiated studies on the replication of the rotaviruses as an Assistant Professor at the University of South Florida in 1984 and moved to his present position in 1987. HIs research has resulted in several publications concerning rotavirus RNA replication. In 1985, he received a three-year R22 award from the NIH to pursue studies on rotavirus replication. The grant was competitively renewed in 1989 for a period of 5 years. The Department was recently awarded an NIH training grant for graduate students and post-doctorates of which the applicant is a co-P.I. The applicant's immediate goal are to further develop his research program aimed at understanding processes involved with the replication of the genome of the rotaviruses. His long term goals are to remain in academia concentrating his research efforts on the development of a research laboratory that has a significant positive impact on elucidating events in the relatively heavy teaching and committee responsibilities allowing him the opportunity to focus more energy into pursuing his research goals. The award would also provide the time required to establish research collaborations with investigators at other universities and towards the training of graduate students and post-doctorates. His application for an RCDA has the support of his chairman, Dr. J. Wayne Streilein, who has agreed to reduce Dr. Patton's departmental obligations in the event that an award is made. Rotaviruses are segmented, double-stranded RNA (dsRNA) viruses that are recognized as causative agents of acute gastroenteritis in a wide variety of animals including man. Despite their pathogenic importance, the basic molecular biology of the rotaviruses is not well understood. In previous work, Dr. Patton developed a cell-free system which supports simian rotavirus SA11 RNA replication and transcription. The synthesis of viral dsRNA in this system is asymmetrical with viral mRNA serving as the template for minus-strand synthesis. The system has allowed the identification and description of subviral particles that synthesize dsRNA (replicase particles). The data indicate that replicase particles are heterogenous with respect to size, density and protein composition. Replicase particles appear to share in common the structural proteins VP1 and VP3 and the nonstructural proteins NS35, NS34 and NS26. Some replicase particles, in addition to the common proteins, also contain VP2 while others contain VP2 and VP6. This heterogeneity apparently arises from the fact that as replicase particles synthesize dsRNA, they concurrently undergo morphogenesis into single-shelled particles by the sequential addition of first VP2 and then VP6 to particles that contain the structural proteins VP1 and VP3. The focus of the research proposed by Dr. Patton is to characterize more completely the structure of rotavirus replicase particles, the function of proteins associated with replicase particles, and the recognition signals of viral mRNA that allow their replication by replicase particles.